- Father Fermín Lasuen was a Spanish missionary in the Americas.
- He was born at Vitoria in Alava, Spain and joined the Franciscans, and was ordained in 1752.
- In 1758 he volunteered to work in America. He arrived in Mexico in 1761 and went to Baja California in 1768.
- Following the Mission San Diego de Alcala in 1769, he went to Northern California in 1773. He worked in San Diego and remained there until 1775.
- He helped build Mission San Juan Capistrano before Father Luís Jayme was murdered. Kumeyay Indian unrest forced Lausen to return to San Diego and the general withdrawal with the Spanish.
- At the end of 1776 he went to San Luis Obispo before returning to San Diego in 1777 when he was ordained as a minister there.
- He was appointed the second President of the missions in California in 1785, replacing Junipero Serra , and transferred to the Mission San Carlos Borromeo de Carmelo. On his death he was succeeded by Father Pedro Estevan Tapis.
